Staff on zero-hours contracts earn £6 an hour less than those working on other contracts, new research published ahead of a summit on the controversial zero-hour arrangements has indicated.
Labour is bringing together trade unions and employers after the revelation that a million people could be employed through the controversial contracts, under which staff are not guaranteed hours of work nor benefits and can be tied to just one employer.
According to official figures analysed by the Resolution Foundation, zero-hours workers are paid an average of £9 an hour, compared to £15 for other employees.
Labour said the summit, to be held in London, was aiming to discuss the arrangements' growth and how to crack down on their "abuse".
Shadow business secretary Chuka Umunna said: "New evidence highlights that there could be hundreds of thousands more people on zero-hours contracts than previously thought. That's hundreds of thousands of people in insecure work earning far less than average pay.
"Flexibility works for some, but the danger today is that too often insecurity at work becomes the norm.
"The huge spike in the use of zero-hours contracts has brought increased reports of abuses and bad practice. There should be zero tolerance of such abuse.
"That is why Labour has convened this important summit bringing together representatives of employers and employers to consider what action must be taken. In contrast, this Tory-led Government has refused to have a proper and full consultation on the rise of zero-hours contracts or to treat this issue with the seriousness which it deserves."
Business Secretary Vince Cable has ordered a review of zero-hours contracts following growing controversy over their use, ruling out an outright ban but pledging to look at the "exclusivity" clause tieing a staff member to an individual employer.